Malignant tachyarrhythmia, for example, ventricular fibrillation (VF), is an uncoordinated contraction of the cardiac muscle of the ventricles in the heart, and is the most commonly identified arrhythmia in cardiac arrest patients. If this arrhythmia continues for more than a few seconds, it may result in cardiogenic shock and cessation of effective blood circulation. As a consequence, sudden cardiac death (SCD) may result in a matter of minutes.
In patients at high risk of ventricular fibrillation, the use of an implantable cardioverter-defibrillator (ICD) system has been shown to be beneficial at preventing SCD. An ICD system includes an ICD, which is a battery powered electrical stimulation device, that may include an electrical housing electrode (sometimes referred to as a can electrode), that is coupled to one or more electrical stimulation leads. The electrical stimulation leads may be placed within the heart, within vasculature near the heart (e.g., within the coronary sinus), attached to the outside surface of the heart (e.g., in the pericardium or epicardium), or implanted subcutaneously above the ribcage/sternum. If an arrhythmia is detected, the ICD may generate and deliver a pulse (e.g., cardioversion or defibrillation shock) via the electrical stimulation leads to shock the heart and restore its normal rhythm.